U8185
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-03-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
25
Analysis
The U8185 uses the PM8029 solution for its charging management. The following figure
shows the internal structure of the PM8029. The PM8029 has three charging states: trickle
charging, constant current charging, and constant voltage charging. A universal charging
channel is used: VEXT_DC→VCHG→Q201, pin3→VBAT
External PMOS is controlled through BAT_FET_N to implement the charging functions
including trickle charging, constant current charging, constant voltage charging, and pulsed
charging. The following figure shows a common charging curve.